Geothermal Giant

Plumbers connect the -in heat exchanger coils to the header prior to transporting it to the 15-acre lake.

Mechanical Inc. plumbers lift the 2-in. high-densiy polyethylene piping onto the manifold room floor. It will be trimmed and fitted with a flange, then connected to the corresponding 2-in. drop.

The team at Mechanical, Inc., Freeport, IL, has been getting lots of on-the-job boating practice, thanks to a sizable geothermal project for an area hospital. Mechanical was chosen to install the geothermal HVAC system for Sherman Hospital’s $310 million replacement hospital in Elgin, IL. Scheduled to open in late 2009, the hospital will be mainly heated and cooled by geothermal energy from a 15-acre artificial lake next to the facility.

“The geothermal lake was a wise choice, both economically and ecologically,” says Brian Helm, president of Mechanical, Inc.

Mechanical, Inc. is working with Walsh Construction Co., Chicago, IL, the construction manager for the replacement hospital. Project executive Larry Voss is overseeing the project for Mechanical, Inc. The geothermal system will save an estimated $1 million in annual energy costs.

“Over the last two years, since the original design, prices have only escalated,” says Dawn Stoner, project specialist for Sherman Hospital. “We see this not only as a great savings, but it also allows us to use a renewable energy source. This is a great decision for any facility, big or small,” Stoner says.

According to industry estimates, buildings using geothermal energy consume up to 40% less energy than other high-efficiency buildings.

How the Geothermal Lake Saves Energy The heating and cooling system includes 275,000 ft. of two-inch piping in the geothermal heat exchanger. Mechanical, Inc. is also installing the medical gas piping and plumbing in the facility.

“Sherman Hospital will be the first hospital in Illinois to build a geothermal lake,” says Selena Worster, project manager for Mechanical, Inc. The project will be one of the largest lake loop heat pump system in the U.S.

Solar energy is absorbed by the surface layer of the 17-ft. deep geothermal lake, resulting in a natural thermocline — . and a relatively consistent temperature at the bottom of the lake. A thermocline is a thin but distinct layer in a large body of water, such as an ocean or lake, in which temperature changes more rapidly with depth than it does in the layers above or below.

A natural clay liner known as betonite was added to prevent water from leaking through the ground. The water level in the artificial lake has to maintain a 17 ft. level to handle the heat exchange between the lake water and the methanol in the pipe.

Water and methanol-filled coils of piping — called heat exchanger rafts — were dropped to the floor of the lake. The steady temperature at the bottom of the lake will be the heating and cooling source for the solution passing through the coils. The solution is circulated by a lake loop heat-pump system.

When the circulating solution reaches the water source heat pumps, the energy is converted to warm or cool air, regulating the temperature of most of the hospital’s rooms. The emergency room and surgical suites will employ a traditional heating and cooling system, since they require cooler temperatures.

Navigational Challenge Worster tells Contracting Business the project’s greatest installation challenge was in working in a body of water on an open, windy construction site.

“The crew was getting blown around on the lake, and at times we had to use two boats on one side of the heat exchanger rafts. This wasn’t something we had done before, so there was a pretty steep learning curve for the first three or four days,” Worster says.

The geothermal portion of the project is scheduled to be completed by August 2008. The entire project is slated for completion late in 2009.

A Mechanical, Inc. contractor moves the heat exchanger raft into position. A portion of the Sherman Hospital construction site appears in the background.

Mechanical Inc.’s plumbing crew positions the lifting frame and geothermal heat exchanger raft as it’s set into the artificial lake near Sherman Hospital.

Selena Worster is a U.S. Green Building Council (USGBC) Leadership in Energy and Environmental Design (LEED®) Accredited Professional (AP), with a green contractor certification from the City of Chicago. She advises contractors seeking green projects to be staffed with one or more LEED APs. If a contractor has a background in green building, be prepared to validate that the buildings are performing as designed.

Worster sees the Sherman Hospital project as the beginning of a greener future for the Midwest, and ultimately, the U.S.

“More businesses are embracing green building. Hopefully this project will inspire other businesses to pursue their own green solutions,” she says.

Mechanical, Inc. was founded in 1968, and is one of the top 50 mechanical contracting firms in the U.S. It has completed projects up to $25 million in 23 states.

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